Is it okay to install 2 GFCI feed through outlets in 1 double gang box? With both GFCIs installed there is only about 1/4" between the side terminals due to there bulky size. Just want to make sure it's okay.

Technically you will be OK according to box fill assuming that you used a 2-gang plastic or 232 metal 4" square with 1/2" ring, however you will find it to be rather difficult to make it all fit and get the cover on nicely. A little trick I use is inserting a control screwdriver into the ground hole to persuade the receps back to straight as the #12 will provide a great deal of resistance in cooperating.